I switched spontaneously at one point. when I was a kid, they though me the 1hb, and I used it exclusively in the beginning, but later I think by watching great 2hbs I started to imitate them. now I use the two-hander 90% of the time, but every now and then I hit it with one hand, usually when I am set nicely for the ball and want to hit cross-court. I use slice with one hand a lot though.
for me it was always easier to watch someone's strokes and copy them, than when people were explaining me how to do it, that is how I learned how to hit two handed backhand(plus practice against the wall of course). if you can learn that way, I suggest you find some videos of Nalbandian, excellent technique. Venus Williams also I think has a very simple but effective motion on her backhand, it could be useful to study.